Convert Light years to millimeters
1 light year = 9.460730e18 millimeters · mm = ly × 9,460,730,473,000,000,000
When you need this conversion
This conversion goes from light years, the astronomical distance light travels in a year, to millimeters, the metric unit used for hardware, engineering drawings, and anything needing sub-centimeter precision. Both measure the same physical quantity, so the conversion is exact — the difference is which unit your source, tool, or region happens to use.
Light years to millimeters conversion table
| Light years (ly) | Millimeters (mm) |
|---|---|
| 1 ly | 9.460730e18 mm |
| 2 ly | 1.892146e19 mm |
| 3 ly | 2.838219e19 mm |
| 5 ly | 4.730365e19 mm |
| 10 ly | 9.460730e19 mm |
| 15 ly | 1.419110e20 mm |
| 20 ly | 1.892146e20 mm |
| 25 ly | 2.365183e20 mm |
| 50 ly | 4.730365e20 mm |
| 75 ly | 7.095548e20 mm |
| 100 ly | 9.460730e20 mm |
| 250 ly | 2.365183e21 mm |
| 500 ly | 4.730365e21 mm |
| 1,000 ly | 9.460730e21 mm |
The formula
mm = ly × 9,460,730,473,000,000,000Because both units measure length, the conversion is a single multiplication by a fixed factor. That factor never changes, so the result is exact.
Convert the other way
Millimeters to light years →Related length conversions
- Micrometers to millimeters
- Millimeters to micrometers
- Centimeters to inches
- Centimeters to feet
- Meters to kilometers
- Kilometers to meters
- Inches to centimeters
- Feet to centimeters
- Feet to yards
- Yards to feet
- Centimeters to millimeters
- Meters to millimeters
Frequently asked questions
- How many millimeters are in a light year?
- There are 9.460730e18 millimeters in 1 light year. The formula is mm = ly × 9,460,730,473,000,000,000.
- How do you convert light years to millimeters?
- Use the formula mm = ly × 9,460,730,473,000,000,000. For example, 10 light years equals 9.460730e19 millimeters.
- Is the light years to millimeters conversion exact?
- Yes. Light years and millimeters are both units of length, related by an exact defined factor. Displayed results are rounded for readability.
- What is ly short for?
- ly is the standard symbol for light year. mm is the symbol for millimeter.